"This article talks about the two styles of HP print heads and the best and easiest methods to refill them. For example, the fixed on cartridge type used in the HP Envy 4524, or the fitted to printer version used in the Officejet 4510. We debate the logic in making single use print head cartridges, and how refilling them can reduce landfill." There has been a long tradition of refilling HP cartridges. Possibly because a high percentage of HP cartridges have a fixed print head, which adds tremendously to the overall price of the cartridge. That, and the fact that...